Problem
1. Draw a graph that cannot be written down on a piece of paper without two edges crossing.
2. Write a program to delete an edge from a graph represented with adjacency lists.
3. Write a version of Si 1ist that keeps the adjacency lists in sorted order of vertex index. Discuss the merits of this approach.
4. Draw the depth-first search forests that result for the example in the text when dfs scans the vertices in reverse order (from V down to 1), for both representations.